In 1918, shortly after the Soviet Socialist Revolution in October, the Red Army soldier Savelyev went to Moscow and was assassinated by counter-revolutionaries at a small station. The sons Vasya and Misha have just lost their mothers, and now they have lost their fathers, and they have no choice...
The Public Security Bureau intercept a telegram notifying foreign agents to retrieve the "110 secret". Shi Yan, head of the Reconnaissance Section, starts a campaign of counter-espionage, but one of his agents is soon killed on board a train.
